KR101045920B1 - How reciprocating internal combustion engines work - Google Patents

Abstract

According to the invention, a method is proposed for the operation of a reciprocating internal combustion engine 1, in particular a large diesel engine, which is scavenged in the longitudinal direction. The reciprocating internal combustion engine 1 includes a cylinder 2 having a scavenging air opening configured in the form of an exhaust valve 3 and a scavenging slot 4 and exhaust gas from the combustion chamber 22 of the cylinder 2. A supercharger group (7) for compressing air (11) with a turbine (9) driven by it, in which the piston (5) is in top dead center with a bottom dead center position (UT) It is possible to reciprocate along the movable surface 6 between the positions OT, and the compressed air is supplied to the combustion chamber 22 of the cylinder 2 through the scavenging slot 4 as scavenging air 12. At least one cylinder 2 of the reciprocating internal combustion engine 1 scavenged in the longitudinal direction is operated according to the four-stroke method.

4-stroke, internal combustion engine, diesel engine, scavenging, preliminary scavenging, combustion chamber, cylinder, turbine, supercharger, exhaust gas

Description

How a reciprocating internal combustion engine works {A METHOD FOR THE OPERATION OF A RECIPROCATING INTERNAL COMBUSTION ENGINE}

1 is a schematic drawing of the main part of a large diesel engine with a supercharger group.

2A is a schematic diagram showing a four-stroke method having a preliminary scavenging stage and a main scavenging stage.

FIG. 2B is a view like FIG. 2A, in which the intake valve is not closed in the preliminary scavenging step.

3A is a schematic diagram showing another four-stroke method having a preliminary scavenging stage and a main scavenging stage.

FIG. 3B is the same view as FIG. 3A, showing a step in which the intake valve is not closed in the preliminary scavenging step.

4 is a schematic diagram showing a two-stroke method with a preliminary scavenging step.

The present invention relates to a reciprocating internal combustion engine operated according to a method of operating a reciprocating internal combustion engine and a method according to the first half of the independent claim of each category.                         

In order to increase the output of reciprocating internal combustion engines, such as large diesel engines for ships or stationary installations for the generation of electrical energy, a group of superchargers, usually composed of exhaust gas turbochargers, after the combustion cycle It is introduced into the combustion chamber of the cylinder under increased pressure and some of the heat energy of the exhaust gas is used to leave the cylinder's combustion chamber after the combustion cycle. For this purpose, hot exhaust gas is supplied from the combustion chamber of the cylinder to the supercharger group by opening the exhaust valve. The group of superchargers consists essentially of a turbine driven by hot exhaust gases entering the turbocharger under pressure. The turbine drives a rotor, whereby fresh air is sucked in and compressed. A charge cooler with a diffuser, a water separator and an inlet receiver is arranged at the bottom of the turbine with the rotor as a compressor, a device also commonly referred to as a turbocharger. From here, compressed fresh air, also known as charge or scavenging air, is finally fed into each cylinder of a large diesel engine. The fresh air supply can thus be increased and the efficiency of the combustion process in the combustion chamber can be increased by the supercharger group described above. Depending on the type of large diesel engine, the infeed of air occupies different positions in the cylinder. For example, in a two-stroke engine scavenged in the longitudinal direction, air is introduced into the combustion chamber of the cylinder through a scavenging slot disposed on the movable surface in the lower region of the cylinder. In a four-stroke engine, the air supply is introduced into the combustion chamber of the cylinder through one or more intake valves, which are generally arranged in the cylinder head, and the two-stroke engine is generally used instead of the scavenging slot in the lower region of the cylinder. It is known to fit into the intake valve.

Since the turbines of the supercharger group are driven only by hot exhaust gases exiting the combustion chamber of the cylinders, only known turbocharger groups for large diesel engines do not operate efficiently, especially immediately after starters or below any speed of rotational limits. This means, for example, that the exhaust gas generated during the previous combustion process is removed from the cylinder chamber, among other things, that the combustion chamber of the cylinder is not supplied with sufficient fresh air during the scavenging cycle and therefore in a sufficient amount of fresh air in the next combustion cycle. It means that it is only expected to an insufficient degree, with a result that cannot be used. The group of superchargers is thus generally complemented by one or more additional mechanical or electric auxiliary superchargers to achieve a corresponding torque increase below the rotational speed limit so that the reciprocating internal combustion engine can be operated more efficiently. A secondary supercharger generally draws air from a first chamber disposed underneath the air supply cooler and delivers air to a second chamber through which the air can also flow through the scavenging slot into the combustion chamber of the cylinder. Backflow of air into the first chamber is prevented by protections consisting of flaps. Said auxiliary superchargers are often configured as electric fans, each with a power of up to 200 kW, and generally have rotational limits obtained between approximately 10% to 50%, in particular between 30% and 35% of the total load capacity of large diesel engines. Support or replace exhaust turbochargers at speeds below. If the speed of the rotational limit is exceeded, the auxiliary supercharger may generally be unnecessary, i.e. the auxiliary supercharger is switched off and the engine is only supplied by the exhaust gas turbocharger. In this state, ie after switching off of the subsupercharger, the flap opens and thus enables direct discharge of the air supply from the first chamber arranged in the lower part of the air supply cooler to the second chamber, and the air Is supplied to the scavenging slot.

Although improvements in cylinder scavenge can be achieved by the use of an auxiliary supercharger for the support of the exhaust gas turbocharger in the low load region, nevertheless the combustion chamber of the cylinder is only insufficiently scrubbed by the known two-stroke method in low load operation, Fresh air may not be available in a sufficient amount in the next combustion cycle, or a very large amount of fresh air is supplied to the combustion chamber at low speed rotation. This means that the amount of air supplied cannot be controlled or adjusted in a known manner for the operation of the reciprocating internal combustion engine.

In addition, the use of additional auxiliary superchargers for the support of the exhaust gas turbocharger in low load operation has practical problems. In addition to the purchase cost for the auxiliary supercharger, an additional device must be installed for its control or adjustment. The construction of the intake receiver is relatively complicated due to the above-mentioned flap which is indispensable to the backflow blocking member during the operation of the auxiliary supercharger. Additional devices inherently require additional service and repair efforts, along with associated additional costs for operating means, spare parts and personnel. In addition, the division of the intake receiver inside the first space and the second space separated by the auxiliary supercharger and the flap is generally short and occupies a relatively large space and increases the weight. Also, the operation of the auxiliary supercharger is more undesirable from an energy point of view, for example, because the electrical energy required for the operation of the electric secondary supercharger must be used. This means that the operation of the subsupercharger will eventually increase fuel consumption, further due to the added weight.

It is therefore an object of the present invention to enable more efficient operation of the reciprocating internal combustion engine, in particular in the load region below a preset rotational speed limit, and in particular without the need for additional mechanical, electrical or other auxiliary loaders, reciprocating internal combustion engines, in particular large To provide a method for the operation of a diesel engine. Another object of the present invention is to provide a reciprocating internal combustion engine operating according to the present invention.

The subject matter of the present invention which satisfies these objectives in mechanical method and apparatus relations is given by the features of the independent claims of each category.

Each dependent claim relates to a particularly preferred embodiment of the invention.

According to the invention, as an example, a method of operating a reciprocating internal combustion engine, in particular a large diesel engine, which is scavenged in the longitudinal direction is proposed. The reciprocating internal combustion engine scavenged in the longitudinal direction includes a group of air compressor superchargers having a cylinder having a scavenging air opening configured in the form of an exhaust valve and a scavenging slot, and a turbine driven by exhaust gas from the combustion chamber of the cylinder. Wherein in the cylinder a piston can reciprocate along a movable surface between a bottom dead center position and a top dead center position, the compressed air is supplied to the combustion chamber of the cylinder through the scavenging slot as scavenging air, At least one cylinder of the reciprocating internal combustion engine scavenged in the longitudinal direction is operated at at least one first settable limit speed in accordance with the four stroke method.

Preferably the method according to the invention is controlled or controlled in such a way that the action of the exhaust valve and the timing of fuel injection are adjusted in the lowest load range, for example arranged below a first settable speed limit after the start of a large diesel engine. It is used in the operation of large diesel engines, in particular crosshead large diesel engines, which can be regulated. The lowest load range may include, for example, a load range of up to approximately 10% of the total load output of the reciprocating internal combustion engine that can be reached at maximum, but is limited to up to 10% of the total load output that can be reached at the maximum. Should not be. The turbocharger, which is supplied with hot exhaust gas from the combustion chamber of the engine's cylinder, has yet to produce the required output at least below the first rotational speed limit and is therefore generally electrically operated and configured as an additional supercharger. Is generally supported. Due to the use of an auxiliary supercharger for the support of the exhaust gas turbocharger in low load operation below the rotational speed limit, the improvement of cylinder scrubbing can be clearly achieved, but in the known two-stroke method the combustion chamber of the cylinder has a low load. Insufficient scavenging in operation allows a sufficient amount of fresh air to be unavailable in the next combustion cycle, or a very large amount of fresh air is supplied to the combustion chamber at low rotational speeds. This means that the amount of air supplied cannot be controlled or adjusted in a known manner for the operation of the reciprocating internal combustion engine. With the use of the method according to the invention, on the one hand, an additional fan consisting of an auxiliary supercharger may be unnecessary, and on the other hand, the supply of fresh air into the combustion chamber of the cylinder can be controlled or regulated, thus reciprocating internal combustion The engine can operate very efficiently.

In another preferred variant of the method according to the invention, the reciprocating internal combustion engine is operated in low load operation below a first settable rotational speed limit according to the four-stroke method. The scavenging air is supplied to the combustion chamber of the cylinder through the scavenging air openings formed in the scavenging slots in the cylinder wall, that is, the reciprocating internal combustion engine is composed of, for example, a large diesel engine with a longitudinal scavenging action.

In a variant of the method according to the invention, the combustion cycle comprises a preliminary scavenging step at least below the first rotational speed limit, so that the exhaust valve is first opened after fuel injection and subsequent combustion has occurred, as described below. Is closed at the preliminary scavenging stage before the scavenging air is introduced into the combustion chamber.

After the compression cycle and subsequent combustion have taken place, hot combustion gases can be used at the operating pressure in the combustion chamber of the cylinder of the reciprocating internal combustion engine, so that the piston is known in the direction of the bottom dead center position corresponding to a crank angle of 180 °. In an expansion cycle. In general, the bottom dead center of a piston where the combustion chamber surrounded by the cylinder, the cylinder head and the piston has the maximum volume has a crank angle of 180 °, whereas a top dead center position where the combustion chamber has a minimum volume has a crank angle of 0 ° or 360 °. In a generally known manner, in the four-stroke method, the bottom dead center position is associated with a crank angle of 180 degrees or 540 degrees and the top dead center position is associated with a crank angle of 0 degrees, 360 degrees or 720 degrees. The exhaust valve is first closed immediately after the combustion process. In the preliminary scavenging stage following combustion, ie before the piston opens the scavenging slot for the first time after combustion, the exhaust valve is opened at a first settable crank angle representing the start of the preliminary scavenging stage, i.e. The start of the preliminary scavenging step is selected such that there is a pressure differential suitable for supplying combustion gas from the cylinder's combustion chamber to the supercharger group when the exhaust valve is opened between the combustion chamber of the cylinder and the exhaust gas stack, and the hot exhaust gas is pressured. Due to the difference, it is selected to enter the turbocharger through the exhaust gas stack and drive the turbine and the rotor there, so that the compressed air is the scavenging air for inflow into the combustion chamber of the cylinder whose scavenging slot is then opened by the corresponding piston. Can be used. This means that part of the thermal energy of the exhaust gas is already used to drive the turbine of the turbocharger in a known manner by opening the exhaust valve in advance before opening the scavenging slots, i.e., before the intake of the scavenging air into the combustion chamber of the cylinder. Means that.

If the pressure difference between the combustion chamber and the exhaust gas stack is substantially extinguished, the exhaust valve is closed again at the second crank angle during the preliminary scavenging step. The volume surrounded by the combustion chamber is enlarged by further movement of the piston in the cylinder in the direction of the bottom dead center position. Since the exhaust valve is closed, the pressure in the combustion chamber drops below the pressure value in the intake receiver, and the scavenging air reaches the combustion chamber of the cylinder through the intake receiver when the scavenging slot is opened by the piston. At the third crank angle, which forms the end of the preliminary scavenging step, the piston finally opens at least partially the scavenging slot so that scavenged air can flow from the intake receiver into the combustion chamber and the exhaust valve is still closed. The scavenged air is sucked into the combustion chamber by the low pressure generated for the intake receiver during the preliminary scavenging step of the combustion chamber. This means that the turbocharger which introduces the scavenged air into the combustion chamber of the cylinder at a preset pressure through the intake receiver is supported by its action by the low pressure generated in the combustion chamber during the expansion movement of the piston in the preliminary scavenging step. Since the maximum pressure difference between the combustion chamber and the intake receiver depends on the crank angle at which the exhaust valve is closed again in the preliminary scavenging stage, the amount of fresh air introduced into the combustion chamber during the preliminary scavenging stage after opening of the scavenging slot indicates that the exhaust valve is preliminary scavenging. It can be controlled or adjusted by presetting the crank angle to be closed in step.

While the exhaust valve obviously opens after the start of the preliminary scavenging stage, it is of course possible to set a certain amount of fresh air that can be used as a whole in the combustion chamber of the cylinder until the next combustion process so that it is no longer closed before the scavenging slot is opened.

Depending on whether a preliminary scavenging step has occurred or whether the exhaust valve is closed again in the preliminary scavenging step, near the bottom dead center position, corresponding to a crank angle of 180 °, the exhaust valve is again opened or opened, In the next compression stroke, which includes a crank angle range between 180 ° and 360 ° and the addressing stage begins, a portion of the exhaust gas is supplied to the supercharger group via the exhaust gas stack via the exhaust valve. Preferably the exhaust valve remains open for the discharge of a portion of the exhaust gas for at least a long time until the piston closes the scavenging slot again during the compression stroke, and then closes at the start of the main scavenging stage at the fourth preset crank angle. . Preferably the action of the exhaust valve is such that the rotational speed of the reciprocating internal combustion engine, the crank angle, the gas pressure inside the combustion chamber of the cylinder, the temperature in the combustion chamber of the cylinder, the rotational speed of the supercharger group, the gas pressure in the supercharger group, and the According to one or more operating parameters of the temperature in the supercharger group, or other operating parameters of the reciprocating internal combustion engine, it is controlled or regulated by a freely programmable control unit.

In this regard, in a preferred variant of the method according to the invention, the crank angle at which the addressing step begins is approximately 270 °. It is also of course also possible for the exhaust valve to close at different values of the crank angle, so that the addressing step starts at different values of the crank angle. The address stage can therefore be started especially at crank angles of just over 360 °.

It is also possible to set a certain amount of fresh air that can be used entirely within the combustion chamber of the cylinder to the next combustion process so that the exhaust valve is no longer closed by the piston until the repeated opening of the scavenging slot, ie the main stage May be omitted.

In this connection, no fuel injection occurs at all in the crank angle range between at least 180 ° and 540 °, ie within the main scavenging stage range. When the main scavenging stage occurs, the mixture of the scavenging air and the gas not yet discharged in the combustion chamber is further displaced from the piston in the direction of the top dead center position until the piston reaches a top dead center position corresponding to a crank angle of 360 °. It is compressed for a very long time by the compression movement. The pressure in the combustion chamber of the cylinder falls back to the exhaust valve which is still closed by the next expansion movement of the piston in the direction of the bottom dead center position at a crank angle of 540 °. An exhaust valve that closes after the scavenging slot closes in a compression stroke between 180 ° and 360 °, so that the path of the piston is in the next expansion stroke between the top dead center position and the repeated opening of the scavenging slot at a crank angle of 360 °. Since it is shorter than the path of the piston, it has a maximum magnitude of the pressure difference between the intake receiver and the combustion chamber according to the value of the crank angle at which the main stage is started, and low pressure is generated in the combustion chamber of the cylinder with respect to the intake receiver. Similar to the preliminary scavenging step, the piston finally partially reopens the scavenging slot so that scavenging air can flow from the intake receiver into the combustion chamber and the exhaust valve is still closed. The scavenged air is sucked into the combustion chamber by the low pressure generated in the combustion chamber with respect to the intake receiver during the main scavenging step. This means that a turbocharger that introduces the scavenged air through the intake receiver into the combustion chamber of the cylinder at a preset pressure is supported by the low pressure generated in the combustion chamber during the expansion movement of the piston in the main stage. it means. Since the maximum pressure difference between the combustion chamber and the intake receiver depends on the start point of the main scavenging stage, the amount of scavenged air introduced into the combustion chamber during the main scavenging stage after opening the scavenging slot is determined by the setting of the start of the main scavenging stage. Can be controlled or adjusted. In contrast, if the main scavenging step is caused by the setting of the amount of scavenged air introduced into the combustion chamber of the cylinder, ie the exhaust valve is at least in the crank angle range between the opening of the scavenging slot at a crank angle of 180 ° and 360 ° or more. If not closed, substantially no low pressure is inherently generated during the corresponding expansion movement of the piston between the crank angle of 360 ° from the combustion chamber of the cylinder of the reciprocating internal combustion engine to the opening of the scavenging slot.

Near the bottom dead center position, at a crank angle of 540 °, the exhaust valve is reopened if it is still closed, the remaining exhaust gas in the next compression stroke is fed to the supercharger group via the exhaust gas stack via the exhaust valve and compressed The cycle begins in a known manner with fuel injection and next combustion.

Thus, the reciprocating internal combustion engine scavenged in the longitudinal direction is operated according to the four-stroke method at a low minimum load range at least below the first preset rotational speed limit, and the four-stroke method can control or regulate the amount of fresh air supplied. . For this purpose, the exhaust valve of at least one cylinder is first opened in a preliminary scavenging step at least below the first rotational speed limit after fuel injection has occurred in the next combustion and before the next introduction of the scavenging air into the combustion chamber of the cylinder. It may then be closed, and in the main stage, the exhaust valve of at least one cylinder may first open and then close at least below the first rotational speed limit.

Above the first rotational speed limit and below the second preset rotational speed limit, the reciprocating internal combustion engine scavenged in the longitudinal direction is operated in the low load range. The low load range may include, for example, a load range between 10% and 35% of the maximum load performance of the reciprocating internal combustion engine that can be attained to the maximum. However, the low load range should not be limited to load ranges between 10% and 35% of the maximum obtainable load performance.                         

Preferably the reciprocating internal combustion engine is operated according to the two-stroke method in the low load range, the two-stroke method in a preferred variant of the method according to the invention, already detailed above in the configuration range of the description of the four-stroke method. It is used in the low load range including the combustion state with the preliminary scavenging stage described. The reciprocating internal combustion engine is securely opened at the start of the preliminary scavenging stage, but the opening of the scavenging slot, for the purpose of setting a certain amount of fresh air, which can be used as a whole in the combustion chamber of the cylinder until the next combustion process. It can of course be operated in the low load range according to the two-stroke method, which was not previously closed.

Above the second preset rotational speed limit, the scavenged reciprocating internal combustion engine finally operates in the high load range. The high load range may include, for example, a load range of 35% or more of the maximum obtainable overall load performance. However, the high load range should not be limited to more than 35% of the maximum attainable load performance.

Preferably the reciprocating internal combustion engine is operated according to a two-stroke method in a high load range, in which a two-stroke method is a particularly preferred variant of the method according to the invention, which can be fully utilized from the combustion chamber of the cylinder to the next combustion process. For the setting of a certain amount of fresh air, the exhaust valve is used in a high load range, including a combustion state, which opens reliably at the start of the preliminary scavenging stage, but never closes before opening the scavenging slot. In another variant, a two-stroke method without preliminary scavenging steps is used in high load operation.

If desired, the reciprocating internal combustion engine can of course also operate in a low load range according to each of the one of the lowest load range and the four stroke method and in the high load range according to one of the two stroke methods described above.

It is also possible to operate the reciprocating internal combustion engine at any rotational speed limit according to one of the four stroke methods described above under any condition. For example, if the maximum performance of the reciprocating internal combustion engine obtainable is not required, the fuel can be saved, for example.

For the realization of a specific operating state, the reciprocating internal combustion engine is configured at each of the three rotational speed limits, i.e. according to one of the two-stroke methods described above or according to one of the four-stroke methods described above. Below one rotational speed limit, it can of course be operated between the first rotational speed limit and the second rotational speed limit and also above the second rotational speed limit.

Finally, in all previously described embodiments and variations of the method according to the invention only all cylinders of the reciprocating internal combustion engine or only some of the cylinders of the reciprocating internal combustion engine according to one of the embodiments or variants described above It is mentioned that it can work. According to another variant of the method according to the invention, when the other cylinder and the same reciprocating internal combustion engine do not need the maximum achievable performance of, for example, the reciprocating internal combustion engine, or when fuel is to be saved, for example. It is especially possible to work at the same time.

A reciprocating longitudinal combustion engine, in particular a large diesel engine, according to the present invention operated in accordance with the present invention comprises a cylinder having a scavenging air opening configured in the form of an exhaust valve and a scavenging slot, and exhaust from the combustion chamber of the cylinder. A group of air compression superchargers with a gas driven turbine, wherein within the cylinder a piston can reciprocate along a moving surface between a bottom dead center position and a top dead center position, wherein the compressed air is scavenged air And is supplied to the combustion chamber of the cylinder through the scavenging slot.

The invention will be explained in more detail below with reference to the accompanying drawings.

FIG. 1 shows a schematic view of the main part of a large diesel engine, consisting of a large diesel engine with a longitudinal sweep and with the next supercharger group 7 indicated as a whole as a reference 1. .

In general, a large diesel engine 1 comprises a plurality of cylinders 2 having a cylinder head 21 and an outlet valve 3 arranged therein, in which the cylinder 2 The piston 5 is capable of reciprocating between the bottom dead center position UT and the top dead center position OT along a running surface 6, the top dead center position OT of the piston 5 being Depending on whether the engine is operated according to the two-stroke method or the four-stroke method, the crank angle K _W is usually 0 °, 360 ° or 720 ° and the bottom dead center position (UT) of the piston 5 is Crank angle K _W is 180 ° or 540 °. The cylinder 2 and the piston 5 with the cylinder head 21 form the combustion chamber 22 in a known manner. At the bottom of the cylinder 2, a plurality of scavenging air openings consisting of scavenging slots 4 are provided. Depending on the position of the piston 5, the scavenging slot 4 is covered by the piston or opened by the piston. Fresh air, called scavenging air 12, can flow into the combustion chamber 22 of the cylinder 2 through the scavenging slot 4. The exhaust gas 8 generated by combustion is an exhaust gas stack 13 which connects the exhaust valve 3 with the supercharger group 7 via an exhaust valve 3 disposed in the cylinder head 21. Flows through). The supercharger group 7 is a major component in a known manner, comprising a rotor 10 for the compression of air 11 and a turbine 9 for driving the rotor 10. And the rotor 10 is connected in a substantially fixed manner to the turbine 9 by means of a shaft 91. The turbine 9 and the rotor 10 are arranged in a housing and form a turbocharger 14. The turbine 9 is driven by introducing hot exhaust gas 8 from the combustion chamber 22 of the cylinder 2. In order to load the scavenging air 12 into the combustion chamber 22 of the cylinder 2, air 11 is sucked through the suction stack 15 by the rotor 10 and the turbocharger It is compressed at 14. The compressed air is passed from the turbocharger via a downstream diffuser 16 and a charge air cooler 17 via a pressure line 18 to an inlet receiver ( 19) Moving inside, the compressed air finally enters the combustion chamber of the cylinder 2 through the scavenging slot 4 as scavenging air 12 under elevated pressure.

Figures 2a, 2b, 3a and 3b schematically show one embodiment of the four-stroke method at a particular rotational limit speed of the reciprocating internal combustion engine according to the invention, respectively, Figures 2a, 2b, 3a and 3b. The method shown in FIG. 3 may be used, if desired, below the first rotational speed limit, or between the first rotational speed limit and the second rotational speed limit, or above the second rotational speed limit. 3A and 3B show that the exhaust valve 3 closes at the value of the crank angle K ₆ , which is 360 ° or more, at the start of the main stage H. Unlike the variant shown in FIG. 2, the crank angle according to FIGS. 2A and 2B has a value of less than 360 °. As will be explained in more detail below, the addressing stage H according to FIGS. 3a and 3b can thus be started in this way also in accordance with the crank angle K _{6 of} more than 360 ° according to FIGS. 3a and 3b.

A variation of the four-stroke method shown in FIGS. 2A and 2B is that the address stage V starts at a crank angle of less than 360 ° in FIGS. 2A and 2B and starts at a crank angle of 360 ° or more in FIG. 3A. Because only substantially different, these variants will be discussed as follows. Their differences will be pointed out in detail.

In a variant of the four-stroke method according to the method of the invention shown in FIGS. 2A and 3A, as explained below, the exhaust valve 3 is first opened, at least after the fuel injection and combustion has occurred, the cylinder It is closed in the preliminary scavenging stage V before the scavenging air 12 flows into the combustion chamber of (2). After the compression cycle and subsequent combustion processes, hot combustion gases can be used in the combustion chamber 22 of the cylinder 2 of the reciprocating internal combustion engine 1 under operating pressure so that the piston 5 has a crank angle of 180 °. Is moved in an expansion cycle in a known manner in the direction of the bottom dead center position UT. In general, in the structure of this application, in the two-stroke method, the combustion chamber 22 formed by the cylinder 2, the cylinder head 21 and the piston 5 has a maximum volume 5 of the piston 5. The bottom dead center position UT of has a crank angle of 180 degrees, whereas the top dead center position OT of which the combustion chamber 22 has a minimum volume has a crank angle of 0 degrees or 360 degrees. In the four-stroke method, in a generally known manner, the bottom dead center position UT is associated with a crank angle of 180 degrees or 540 degrees and the top dead center position OT is associated with a crank angle of 0 degrees, 360 degrees or 720 degrees. The exhaust valve 3 is closed immediately after the combustion process at the crank angle K ₁ . After the preliminary scavenging step V after combustion, that is, before the piston 5 opens the scavenging slot 4 for the first time after combustion, the exhaust valve 3 is opened at a preset crank angle K ₂ . The crank angle K ₂ represents the start of the preliminary scavenging stage V, and the crank angle K ₁ represents the exhaust gas as the exhaust valve 2 opens between the combustion chamber 22 and the exhaust gas stack 13. (8) is selected to be suitable for supplying the supercharger group 7 from the combustion chamber 22 of the cylinder 2, and there is a pressure difference so that part of the hot exhaust gas 8 due to the pressure difference causes a part of the exhaust gas stack. Entering the turbocharger 14 through 13, there drives the turbine 9 and the rotor 10, through which the compressed air is passed through the scavenging slot 4, which is opened by the piston 5 at this point. It is used as the scavenging air 12 which flows into the combustion chamber 22 of the cylinder 2.

If the pressure difference between the combustion chamber 22 and the exhaust gas stack 13 is substantially balanced, the exhaust valve 3 closes again during the preliminary scavenging step V at a pre-set crank angle K ₃ . . The volume surrounded by the combustion chamber 22 is enlarged by further movement of the piston 5 in the cylinder 2 in the direction of the bottom dead center position UT at a crank angle K _W of 180 °. Since the exhaust valve 3 is closed, the pressure in the combustion chamber 22 drops below the pressure value in the intake receiver 19, and when the scavenging slot 4 is opened by the piston 5, the scavenging air 12 ) Enters the combustion chamber 22 of the cylinder 2 via the intake receiver 19. At the crank angle K ₄ , the piston 5 is a scavenging slot 4 so that the scavenging air 12 can flow from the intake receiver 19 into the combustion chamber 22 with the exhaust valve 3 closed. At least partially open. The scavenging air 12 is sucked into the combustion chamber 22 by the low pressure generated for the intake receiver 19 during the preliminary scavenging step V of the combustion chamber 22. This is because the turbocharger 14 which introduces the scavenging air 12 into the combustion chamber 22 of the cylinder 2 through the intake receiver 19 under a pre-determinable pressure is applied to the piston 5 in the preliminary scavenging step V. It means that the function is supported by the low pressure generated in the combustion chamber 22 during the expansion movement of. Since the maximum pressure difference between the combustion chamber 22 and the intake receiver 19 depends on the crank angle K ₃ at which the exhaust valve 3 is closed again in the preliminary scavenging stage V, the opening of the scavenging slot 4 is achieved. The amount of fresh air introduced into the combustion chamber 22 during the post preliminary scavenging stage V can be controlled or adjusted by presetting the crank angle K ₃ at which the exhaust valve 3 is closed in the preliminary scavenging stage V. .

Near the bottom dead center position UT, which corresponds to a crank angle K _W of 180 °, the exhaust valve 3 opens again at the crank angle K _5, extending the crank angle range between 180 ° and 360 °. In the next compression stroke, which comprises, a part of the exhaust gas 8 is supplied to the supercharger group 7 via the exhaust gas stack 13 via the exhaust valve 3. Preferably the exhaust valve 3 remains open for at least a long time until the piston 5 closes the scavenging slot 4 again during the compression stroke and then the crank angle K which represents the start of the main scavenging stage H. _With the closing of the exhaust valve 3 at ₆ ), it is closed at a preset crank angle K6. Preferably, the exhaust valve 3 has a rotational speed of the reciprocating internal combustion engine 1, a crank angle K _W , a gas pressure in the combustion chamber 22 of the cylinder 2, a temperature in the combustion chamber of the cylinder 2, Control unit freely programmable according to the operating parameters of at least one of the rotational speed of the supercharger group 7, the gas pressure of the supercharger group, and the temperature of the supercharger group 7, or other operating parameters of the reciprocating internal combustion engine 1. controlled or controlled by a control unit (not shown).

In this regard, in a preferred variant of the method according to the invention, the crank angle K ₆ is generally 270 °. It is also possible for the exhaust valve 3 to close at a different value of the crank angle K ₆ , so that the main stage H starts at a different value of the crank angle K ₆ . As shown in FIG. 3A, the address stage H can also start particularly at a crank angle K ₆ of 360 ° or more.

Fuel injection does not occur at all within at least the main stage H range. The mixing of the scavenging air 12 and the exhaust gas 8 not yet discharged in the combustion chamber 22 is performed at the top dead center position OT where the piston 5 corresponds to a crank angle K _W of 360 °. Until reaching, it is compressed for a very long time by the further movement of the piston 5 in the direction of top dead center position OT corresponding to a crank angle K _W of 360 °. The pressure in the combustion chamber 22 of the cylinder 2 falls back to the exhaust valve 3 which is still closed due to the next expansion of the piston 5 in the direction of the bottom dead center position UT at a crank angle of 540 °. The exhaust valve 3 is still closed even before repeated opening of the scavenging slot 4 at a crank angle K ₇ whose value is greater than 360 °. With the exhaust valve 3 which is closed after the scavenging slot 4 is closed in the compression stroke between 180 ° and 360 °, the path of the piston 5 has a top dead center position OT at a crank angle K _W of 360 °. Since it is shorter than the path of the piston 5 in the next expansion stroke between the repeated openings of the scavenging slot 4, the intake receiver 19 depends on the value of the crank angle K _{6 at} which the main scavenging step H starts. And a maximum pressure difference between the combustion chamber 22 and low pressure is generated in the combustion chamber 22 of the cylinder 2 with respect to the intake receiver 19. Similar to the preliminary scavenging step (V), the piston 5 at least partially reopens the scavenging slot 4 at the crank angle K ₈ so that the scavenging air 12 is discharged from the intake receiver 19. (22) can flow inside, and the exhaust valve 3 is still closed. The scavenging air 12 is sucked into the combustion chamber 22 by the low pressure generated in the combustion chamber 22 with respect to the intake receiver 19 during the preliminary scavenging step (V). This is because the turbocharger 14, which introduces the scavenging air 12 through the intake receiver 19 into the combustion chamber 22 of the cylinder 2 at a pre-set pressure, allows the piston in the preliminary scavenging step V to be opened. It means that the function is supported by the low pressure generated in the combustion chamber 22 during the expansion movement of 5). Since the maximum pressure difference between the combustion chamber 22 and the intake receiver 19 depends on the crank angle K ₆ , which is the starting point of the main scavenging stage H, the main scavenging stage after opening the scavenging slot 4. The amount of scavenging air 12 introduced into the combustion chamber 22 during (H) can be controlled or adjusted by setting the crank angle K ₆ in advance.

Near the bottom dead center position UT, corresponding to a crank angle K _W of 540 °, the exhaust valve 3 is opened again at a preset crank angle K ₉ , and the exhaust gas remaining in the next compression stroke ( 8 is supplied to the supercharger group 7 via an exhaust gas stack 13 via an exhaust valve 3 and with a fuel injection a preset crank angle in which the compression cycle and the next combustion indicate the end of the main stage ( K ₁₀ ) in the known manner.

Figures 2b and 3b show two different variants of the four-stroke method which are preferably used within the construction of the method of the present invention, and variations of the four-stroke method shown in Figures 2b and 3b are shown in Figure 2b. The only difference is that the scavenging step starts at a crank angle of less than 360 ° and at a crank angle greater than 360 ° in FIG. 3A. These two variants are hereby discussed together below. Their differences will be pointed out in detail.

The embodiment of the four-stroke method shown in FIGS. 2b and 3b differs from the variant previously described in FIGS. 2a and 3a only in that the exhaust valve 3 is not closed in the preliminary scavenging step (V). After the fuel injection has occurred with the next combustion and before the next introduction of the scavenging air 12 into the combustion chamber 22 of the cylinder 2, the exhaust valve 3 is preliminary scavenged at the crank angle K ₂ . Opens to the stage. The crank angle K ₂ also inherently here indicates the beginning of the preliminary scavenging stage V. FIG. The exhaust valve 3 is also closed for the first time immediately after the combustion process at the crank angle K ₁ . In the preliminary scavenging step (V) following combustion, before the piston opens the scavenging slot 4 for the first time after combustion, the exhaust valve 3 is opened at a preset crank angle K ₂ , and the crank angle K ₂ is the opening of the exhaust valve 3 between the combustion chamber 22 and the exhaust gas stack so that it is suitable for supplying the exhaust gas from the combustion chamber 22 of the cylinder 2 to the supercharger group 7. And a portion of the hot exhaust gas 8 enters the turbocharger 14 through the exhaust gas stack 13 because of the pressure difference, from which the turbine 9 drives the rotor 10 accordingly. Optionally, compressed air can be used as the scavenging air 12 for introduction into the combustion chamber 22 of the cylinder 2 whose scavenging slot 4 is then opened by the corresponding piston 5.

The pressure difference between the combustion chamber 22 and the exhaust gas stack 13 is substantially balanced. As shown in FIGS. 2B and 3B, the exhaust valve 3 does not close again after the pressure balance is generated between the combustion chamber 22 and the exhaust gas stack 13 during the preliminary scavenging step V. The pressure in 22 does not fall substantially further by further movement of the piston 5 in the cylinder 2 in the direction of the bottom dead center position UT at a crank angle K _w of 180 °. The amount of fresh air that can flow from the intake receiver 19 into the combustion chamber 22 after opening of the scavenging slot at crank angle K ₄ is therefore reduced compared to the variant discussed with reference to FIGS. 2A and 3A. Can be. After opening of the scavenging slot ₄ at the crank angle K ₄ , the piston 5 further moves in the direction of the bottom dead center position UT, as already discussed in detail in FIGS. 2A and 2B, The address stage H occurs after the next fuel injection and combustion. In this regard, in a preferred variant of the method according to the invention, the crank angle K ₆ is approximately 270 °. It is also possible for the exhaust valve 3 to close at a different value of the crank angle K ₆ , so that the main stage H starts at a different value of the crank angle K ₆ . Thus, the address scavenging step H may be started at a crank angle K _{6 of} 360 ° or more, as shown in FIG. 3B. This means that the four-stroke method shown in FIG. 2B starts at crank angle K _w in which the main stage H is less than 360 ° in FIG. 2B, whereas in the method according to FIG. 3B the crank angle K _w is 360 °. Only above means that it is substantially different from the four-stroke method shown in FIG. 3B.

In a particularly preferred embodiment of the method according to the invention, the reciprocating internal combustion engine 1 is especially operated above a first settable limit speed according to a two-stroke method with a combustion state comprising a preliminary scavenging stage (V). .

In figure 4 the corresponding two-stroke method is schematically shown for a large diesel engine. A complete two-stroke cycle is shown in FIG. 4 for the description of the main steps. Position of the cylinder (2) is in the piston 5 in the top dead center position (OT) with a 180 ° crank angle corresponding to the crank angle (K _w) and the bottom dead center position of 0 ° corresponding to the complete two-stroke cycle, It is shown for eight selected crank angles K _w . Because the methods are two-stroke method, the 0 ° crank angle (K _w) is the same as that of a 360 ° crank angle (K _w).

At the crank angle K ₁ , combustion is essentially finished in the combustion chamber 22 of the cylinder 2 after the immediately preceding compression cycle so that hot combustion gas can be used in the combustion chamber 22 at the working pressure and the cylinder ( The piston 5 in 2) is therefore moved in an expansion cycle in the direction of the bottom dead center position UT, starting at the crank angle K ₁ and corresponding to the crank angle K _w of 180 °. The exhaust valve 3 is closed at the crank angle K ₁ . After the occurrence of fuel injection with the next combustion and before the next inflow of the scavenging air 12 into the combustion chamber 22 of the cylinder 2, ie the piston 5 opens the scavenging slot 4 for the first time after the combustion cycle. In the preliminary scavenging stage (V) starting at the pre-settable crank angle K ₂ , the exhaust valve 3 is at the preset crank angle K ₂ with the start of the preliminary scavenging stage V. open, that is more than the pressure in the crank angle (K ₂₎ is a crank on each (K ₂₎ at the same time with opening of the exhaust valve 3, the pressure in the combustion chamber 22 of the cylinder 2 is an exhaust gas stack (13) It is still chosen to be clear. Because of the pressure difference between the combustion chamber 22 and the exhaust gas stack 13, the hot exhaust gas 8 flows through the exhaust gas stack 13 to the turbocharger 14 and from there along the turbine 9 By driving the rotor 10, as described above, the compressed air is introduced into the combustion chamber 22 of the cylinder 2 in which the scavenging slot 4 is then opened by the corresponding piston 5. It may be used as the scavenging air 12 for inflow. This is through the opening of the exhaust valve 3, in a known manner, in which part of the thermal energy of the exhaust gas 8 is released before opening the scavenging slot 4, ie the turbine of the turbocharger 14. 9) means that it is already being used before the introduction of the scavenging air 12 into the combustion chamber 22 of the cylinder.

In crank angle (K ₂₎ somewhat larger crank angle (K ₃₎ than the combustion chamber 22 and exhaust stack a pressure difference between 12 forms a substantially balanced by the exhaust valve (3) is a crank angle (K _It is closed again during the preliminary scavenging stage (V) in ₃ ). Since the maximum pressure difference between the combustion chamber 22 and the intake receiver 19 depends on the crank angle K _w at which the exhaust valve 3 is closed again in the preliminary scavenging stage V, the opening of the scavenging slot 4 is achieved. The amount of fresh air introduced into the combustion chamber 22 during the preliminary scavenging step V is determined according to the rotational speed of the reciprocating internal combustion engine 1, and the crank angle K _w , inside the combustion chamber 22 of the cylinder 2. Gas pressure, temperature in the combustion chamber 22 of the cylinder 2, rotational speed of the supercharger group 7, gas pressure in the supercharger group 7, temperature in the supercharger group 7, the reciprocating internal combustion engine According to other operating parameters of (1), the exhaust valve 3 can be controlled or adjusted by presetting the crank angle K ₃ , which is closed in the preliminary scavenging step V. The volume surrounded by the combustion chamber 22 is enlarged by further movement of the piston 5 in the cylinder 2 in the direction of the bottom dead center position UT, so that the pressure in the combustion chamber 22 is increased by the exhaust valve ( Since 3) is closed, it falls to the pressure in the intake receiver 19. At the crank angle K ₄ , which indicates the end of the preliminary scavenging step V, the piston 5 opens at least a portion of the scavenging slot 4 so that the scavenging air 12 is released from the intake receiver 19. 22) It can flow inside, and the exhaust valve 3 is closed. The scavenging air 12 is sucked into the combustion chamber 22 by the low pressure formed in the combustion chamber 22 in the preliminary scavenging step (V). This is because the turbocharger 14 which introduces the scavenging air 12 into the combustion chamber 22 of the cylinder 2 via the intake receiver 19 at a pre-determinable pressure is provided in the preliminary scavenging step V. It means that the function is supported by the low pressure formed in the combustion chamber 22 during the expansion movement of 5).

Near the bottom dead center position UT of the crank angle K ₅ and before the piston 5 reaches the bottom dead center position UT, the exhaust valve 3 is opened to open the exhaust gas 8 in the next compression cycle. May be supplied to the supercharger group 7 via the exhaust gas stack 13 via the exhaust valve 3. At a crank angle of 180 °, the exhaust valve 3 is still open and the compression cycle starts in a known manner, and the scavenging slot 4 is closed at the same time as the crank angle K ₆₁ is reached. In contrast, the exhaust valve 3 is pre- or after reaching the crank angle K ₆₁ during the compression cycle, i.e. at a preset time after the piston 5 has passed the bottom dead center position UT, Closed on demand.

In another variant of the method according to the invention, before the piston 5 reaches the bottom dead center position UT, the exhaust valve 3 may in particular be closed again after opening the scavenging air opening 4. Because of the further movement of the piston 5 in the direction of top dead center position OT, the air enclosed in the combustion chamber is compressed and the fuel is compressed in a manner known inherently at the pre-settable time by means of injection nozzles (not shown). 22) It enters inside and is followed by combustion of the fuel / air mixture in the combustion chamber 22.

On the other hand, the action of the exhaust valve 3 depends on the rotational speed of the reciprocating internal combustion engine 1, the crank angle K _w , the gas pressure inside the combustion chamber 22 of the cylinder 2, and the cylinder 2. Operating parameters of at least one of a temperature in the combustion chamber 22, a rotational speed of the supercharger group 7, a gas pressure in the supercharger group 7, and a temperature in the supercharger group 7, or the reciprocating internal combustion engine ( According to other operating parameters of 1), they can be controlled or adjusted by a freely programmable control unit (not shown).

By using the method according to the invention for the operation of reciprocating internal combustion engines, in particular large diesel engines, which are scavenged in the longitudinal direction, the improvement of the cylinder scavenging is preferably at a wide load range, ie below the first preset limit speed of the device. The amount of scavenged air achieved and supplied can be controlled or adjusted in accordance with the relevant operating parameters, in particular the rotational speed of the reciprocating internal combustion engine or the rotational speed of the group of superchargers by the action of the exhaust valve.

In addition, by using the method according to the invention, the problem of having an additional auxiliary supercharger for the support of the exhaust gas turbocharger in low load operation is avoided. In addition, the cost of purchasing and manufacturing the auxiliary supercharger and the equipment necessary for its control are thus reduced. The configuration of the intake receiver is not very complicated, in particular because a flap-shaped backflow prevention member may also be unnecessary.

It also eliminates the required service and repair efforts, along with the associated additional costs for operating means, spare parts and personnel. In particular, considerable space and weight are saved with the use of the method according to the invention. In addition, the operation of a reciprocating internal combustion engine without an auxiliary supercharger is further preferred from an energy point of view, since the electrical energy for its operation is no longer needed, which in turn can further reduce costs. The use of the method according to the invention reduces at least fuel consumption of the reciprocating internal combustion engine.

The method for the operation of a reciprocating internal combustion engine, in particular a large diesel engine, according to the invention has the effect of enabling more efficient operation of the reciprocating internal combustion engine, in particular in the load region below a preset rotational speed limit.

Claims (13)

A cylinder 2 having a scavenging air opening configured in the form of an exhaust valve 3 and a scavenging slot 4, and Supercharger group (7) for compressing air (11) with turbine (9) driven by exhaust gas from combustion chamber (22) of cylinder (2) Including, In the cylinder 2 the piston 5 can reciprocate along the movable surface 6 between the bottom dead center position UT and the top dead center position OT, Compressed air is supplied to the combustion chamber 22 of the cylinder 2 through the scavenging slot 4 as scavenging air 12. In the method of operating the reciprocating internal combustion engine 1, in particular a large diesel engine, which is scavenged in the longitudinal direction, At least one cylinder 2 of the reciprocating internal combustion engine 1 scavenged in the longitudinal direction is operated in a low load region below a first rotational limit speed which can be preset according to a four-stroke method, The four-stroke method includes a combustion state having a pre-scavenging phase (V), in which the pressure reduction occurs in the cylinder (2), A method of operating a reciprocating internal combustion engine scavenged in the longitudinal direction, characterized in that. The method of claim 1, At least one cylinder 2 of the reciprocating internal combustion engine 1 scavenged in the longitudinal direction is operated at least at a second rotational speed limit according to the two-stroke method.  Method of operation of a reciprocating internal combustion engine in the longitudinal direction. delete The method according to claim 1 or 2, The at least one cylinder 2 of the reciprocating internal combustion engine 1 scavenged in the longitudinal direction is operated at a low load range that is above the first rotational speed limit and below the second preset rotational speed limit according to the four-stroke method. , The low load range includes a range between 10% and 35% of the maximum load performance of the reciprocating internal combustion engine, which can be obtained at maximum. Method of operation of a reciprocating internal combustion engine in the longitudinal direction. The method according to claim 1 or 2, At least one cylinder 2 of the reciprocating internal combustion engine 1 scavenged in the longitudinal direction is operated at a high load range above the second rotational speed limit according to the four-stroke method, The high load range includes a load range of at least 35% of the total load performance of the reciprocating internal combustion engine attainable to the maximum, Method of operation of a reciprocating internal combustion engine in the longitudinal direction. delete The method according to claim 1 or 2, The four-stroke method includes an address stage (H) Method of operation of a reciprocating internal combustion engine in the longitudinal direction. The method according to claim 1 or 2, The two-stroke method includes a combustion state having a preliminary scavenging stage (V). Method of operation of a reciprocating internal combustion engine in the longitudinal direction. The method according to claim 1 or 2, The exhaust valve 3 of the at least one cylinder 2 is first opened and then closed during the preliminary scavenging step V in the range of at least one preset speed of rotation. Method of operation of a reciprocating internal combustion engine in the longitudinal direction. The method according to claim 1 or 2, The exhaust valve 3 of the at least one cylinder 2 is first opened and then closed in the main stage H in the range of at least one preset rotational speed. Method of operation of a reciprocating internal combustion engine in the longitudinal direction. The method according to claim 1 or 2, The action of the exhaust valve 3 and the timing of fuel injection into the combustion chamber 22 of the cylinder 2 include the rotational speed of the reciprocating internal combustion engine 1, the crank angle K _w , and the cylinder 2. Gas pressure inside the combustion chamber 22, the temperature in the combustion chamber 22 of the cylinder 2, the rotational speed of the supercharger group 7, the gas pressure in the supercharger group 7, and the supercharger group 7. Controlled or regulated in a controlled manner by a freely programmable control unit, in accordance with one or more operating parameters of the temperature within, or other operating parameters of the reciprocating internal combustion engine 1. Method of operation of a reciprocating internal combustion engine in the longitudinal direction. The method according to claim 1 or 2, The exhaust valve 3 opens near the bottom dead center position UT and also closes again before or after reaching the crank angle K ₆ representing the start of the main stage H during the compression cycle. Method of operation of a reciprocating internal combustion engine in the longitudinal direction. A cylinder 2 having a scavenging air opening configured in the form of an exhaust valve 3 and a scavenging slot 4, and Supercharger group (7) for compressing air (11) with turbine (9) driven by exhaust gas from combustion chamber (22) of cylinder (2) Including, In the cylinder 2 the piston 5 can reciprocate along the movable surface 6 between the bottom dead center position UT and the top dead center position OT, Compressed air is supplied to the combustion chamber 22 of the cylinder 2 through the scavenging slot 4 as scavenging air 12. In the reciprocating internal combustion engine 1, in particular large diesel engines, The reciprocating internal combustion engine 1 scavenged in the longitudinal direction is operated according to the method according to claim 1. Reciprocating Internal Combustion Engine.

Images